Coastal Flooding Modelling in Basque Estuaries.
Supervisor: Iñaki de Santiago (AZTI)
The estuary of Txingudi is a complex environment in between ocean and river, exposed to the Basque Coast hydrodynamic. For centuries Txindudi estuary environment has been exposed to anthropogenic pressure with the quasi-complete urbanisation of its natural area. Modifying natural environments to be replaced by human infrastructure is not always without consequences in such environment, inundations have been reported for years and the population is increasingly exposed as the ocean level is rising due to the climate change (ref).

The study of coastal inundation has been starting with the migration to the population to the coast, an important environment for humans and also very touristic (ref). Many models can be used to assess the inundation spread in particular the bathtub model that is a classical model used by many enterprise and research centres. The bathtub model has been used in AZTI to get a first inundation map around Txingudi estuary in the Kostarisk study, but the results needed to be improved as the model used seems to expend to much the inundation area. In particular 10 different scenarios of water elevation corresponding to climate change scenarios have been used.

The model mainly used in this study is a numerical based model named Lisflood FP coming from the university of Bristol. This hydrological model permit to get water depth map from complex raster Lidar images by solving the 1D shallow water equation in between each pixel of the map. This complex model has lots of possibilities, in particular include the tide thanks to non-stationary boundaries and to use bathymetry and complex MDT map surfaces (buildings, human infrastructures visible).

This model has been first tested and then compared to the bathtub model by using the same ten water elevation scenarios. The tide, bathymetry and human infrastructures have been implemented in the Lisflood FP model, to observe how they individually or together influence the expansion of the inundation zone. Bathymetry and buildings have been added thanks to a new MDT map provided by AZTI hydrogeology team. During this study, different parameters were studied, such as the resolution of the maps, to get the most precise possible inundation surfaces.